The invention relates to injection devices and, more particularly, to an injection device for providing for the metered administration of an injectable product.
EP 0 298 067 B1 discloses an injection pen comprising a dual chamber ampoule (or ampule). The pen comprises a base section, a container accommodated by said base section, a drive unit and a metering device. A product dose is dispensed from the container through a needle by advancing in forward direction a piston arranged in said container. The drive unit comprises a driven member projecting into the container, displacing the piston in forward direction upon actuation of the drive unit. The length of the stroke, by which the driven member is displaced in forward direction of the piston in relation to the base section upon actuation of the drive mechanism, is set by means of the metering device. The base section is an enclosure surrounding the container, the drive unit and the metering device. The device, and others generally similar to it, is used for injection or infusion of a generally liquid drug solution.
It is an object of the present invention to provide an injection device for metered administration of an injectable product, such as a liquid drug solution, in particular a medical or cosmetic drug solution such as insulin, wherein the device is configured as simply as possible and is as short in length as possible.
In one embodiment, the present invention provides a device for metered administration of an injectable product including a base section, a container, a drive unit including a driven member projecting into the container, and a metering device for setting the path length of displacement of the driven member in relation to the base section upon actuation of the drive unit, wherein the metering device includes a first and second metering structure arranged in the container, the second being adjustable in relation to the first, and wherein metering is effected by interaction of the first and second metering structures.
In one embodiment, the present invention provides a device comprising a base section, a container accommodated by said base section, a drive unit and a metering device. A product dose is dispensed from the container through a needle by advancing in forward direction at least one piston arranged in said container. The drive unit comprises a driven member projecting into the container, which displaces the piston in forward direction upon actuation of the drive unit. The length of the stroke, by which the driven member is displaced in forward or dispensing direction of the piston in relation to the base section upon actuation of the drive mechanism, is set by means of the metering device.
The base section is preferably an enclosure substantially, but not necessarily, surrounding the container, the drive unit and the metering device. The device is used for injection or infusion of a generally liquid drug solution, preferably a medical or cosmetic liquid. In particular and preferably, the invention refers to a portable device, a so-called injection pen.
According to the invention, at least a first metering means and at least a second metering means, the second one being adjustable in relation to the first, are provided in the container, and metering is effected by interaction of the first and second metering means within the container.
According to the invention, the space of the container located behind the piston, when looked at in forward direction, is used for accommodating the metering means of the metering device. The overall length may be shortened by providing a container that projects at least somewhat over the piston at the rear. This is particularly the case in multi-chamber ampoules in which several in-line chambers are separated from each other by pistons and are closed by a rear piston. Owing to the fact that generally the rear piston is pushed against the front piston(s) for mixing the chamber contents prior to the first injection, a free rear container space is compulsorily or customarily generated.
In a preferred embodiment of the present invention, i.e. in a device comprising said multi-chamber ampoule, the free container space is used for arranging the metering means of the metering device, preferably the complete metering device. In addition, a reduction in components is achieved if the mixing member known per se in such devices, mixing being accomplished according to the prior art by driving the rear piston forward for mixing the chamber contents, is simultaneously formed as a carrier of at least one metering means, thus becoming a component of the metering device.
In a preferred embodiment of the invention, the first metering means""s provided at such a mixing member, and the second metering means is directly provided at the driven member. In this embodiment, metering is directly effected between the two components of the device moved in relation to each other for advancing the piston. The mixing member may be configured as a mixing rod and in this design would be surrounded by the driven member, designed as a driven sleeve. Preferably, however, the mixing member is designed as a mixing sleeve and/or a mixing tube, and surrounds the driven member, thus obtaining the structure of both the drive unit and the metering device.
The metering device is preferably arranged between two components of the metering device projecting into the container, similar to a coulisse guiding.
In one embodiment, the coulisse or link guide system is preferably formed by a recess within the area of an internal circumferential face of the sleeve component and an engaging cam. The recess comprises the first metering means, and the cam the second. In a preferred embodiment, the recess forms a guide channel for the cam.
The components of the metering device, at which the first metering means is formed, may be simply produced in that the recess may be generated by joining several cylindrical bodies, wherein at least one of these bodies is a hollow cylinder or bowl-shaped, respectively. Preferably both bodies are designed as sleeve bodies or bowl-shaped bodies.
A stepped recess is obtained by two cylindrical bodies comprising stepped front faces. Two bowl-shaped bodies may be inserted in-line in forward direction in a third sleeve body, thus forming the stepped recess between them.
Metering by means of an adjusting spindle, however, could also be provided. The spindle drive for metering would be formed by the component comprising the first metering means plus an additional adjusting sleeve, simultaneously acting as a straight guide for the driven member. Said metering mechanisms are known per se in injection pens, but prior to the present invention, they have not been located or arranged within a container of an injection pen.
In one embodiment of the invention, the component of the metering device, at which the first metering means is formed, preferably a mixing member, may be used simultaneously as a transfer member, transferring a forward movement of the driven member to the container. This dual function is applied in so-called auto-injection devices, in which the container is displaced into a frontal position in relation to the base section for inserting the hypodermic needle which is usually firmly attached to the container.
Other objects, features, embodiments and advantages of the device and method of the present invention will become more fully apparent and understood with reference to the following description and appended drawings and claims.